This invention is concerned with film technology and more particularly with window films, which are colored or shaded with a pigment. In accordance with this invention, the optical properties of a window film are altered by use of a pigment in lieu of a dye. By use of the process, structure and composition of this invention window films having low haze levels are produced. In addition to low haze levels this invention is concerned with a window film which has superior light stability and hence a film that has an extended life.
The application or retrofitting of films to windows and other substrates for various purposes is quite common. The films of this invention are applied to windows, for example, polymeric or glass panes. The most common application of the films of this invention is to automotive windows. Films can also be applied to window panes to affect the ability of these panes to absorb or transmit heat or ultraviolet (UV) light. Further, films can be applied in order to change the color of a window pane, it is these colored films with which this invention is concerned. Likewise, films can be applied in order to increase the strength of a window pane and in particular, the ability of the window pane to stay intact after an impact with a foreign object. Films are also applied to window panes in order to alter the ability of the window pane to transmit, absorb or reflect visible and invisible solar radiation. In all applications of films, it is desirable that the haze level of the film be minimal. This invention is concerned with colored window films which have minimal haze and which are extremely light stable. Further this invention is concerned with window films wherein the coloration of the films is effected with a pigment. In the prior art most window films were colored with dyes, which fade when exposed to sunlight. More particularly this invention is concerned with colored window films which in addition to being very light stable have a low haze level. In the prior art pigmented window films have unacceptable haze levels. This haze results from the fact that light is scattered off of pigment particles at an unacceptable rate.